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Topic: Fundamental Extractor PCB (Read 4247 times)

Some time ago I build the E&MM Harmony Generator which was discussed in this thread: http://www.diystompboxes.com/smfforum/index.php?topic=54424.0I was not satisfied with the tracking of this circuit, so I decided to build a fundamental extractor to use in front of the harmony generator.I used the extractor part of the Boss OC-2.Although I have not used it with the harmony generator yet, I've tried it and the tracking is OK all over the fretboard and on different guitars.

I'm pretty sure my schematic is correct.I used ExpressPCB to do the PCB and the schematic.

The PCB part of this application imports the schematic file, so you can do a design check.It highlights the pins you need to connect.Since the one I build using the PCB works fine, I think the schematic is OK.

Furthermore, although I do not completely understand the principle of this circuit, I think that the 2 rightmost opamps are used as comperators.One of them uses a high input to create a high output to reset the flipflop, the other one uses a low input to create a high output to set the flipflop.So one of them needs to have the inputs reversed.

Now, let me get something. The flipflop produce a square wave at the ouput with a frequency equal to the fundamental, BUT we dont want that (do we?) because the square wave has a lot of harmonics that might trick the circuit wich is connected next (harmony generator, octaver, wahtever).So, what is this circuit useful for? Its only to get a stable frequency response all over the fretboard?

So, I've built this for use as the front end of the Harmony Generator, and it works and tracks, but the pulse wave doesn't shut up when I stop playing. Is it supposed to? The harmony generator derives its envelope from the input envelope, so having this constantly running oscillation is probably going to cause the HG to do the same.

Is this how the circuit is supposed to act, or do I have a problem somewhere?